1. Technical Field
The disclosed embodiments relate to a liquid crystal display (LCD) apparatus and a driving method thereof and, in particular, to an active matrix LCD apparatus and a driving method thereof.
2. Related Art
With the progress of technologies, display apparatuses have been widely applied to various fields. Especially for liquid crystal display (LCD) apparatuses, because of having advantages such as low power consumption, less heat, light weight and less radiation, they are gradually taking the place of cathode ray tube (CRT) display apparatuses and widely applied to various electronic products. For example, LCD apparatuses of an in-plane switch (IPS) type or a fringe field switching (FFS) type are commonly used to portable electronic products, such as smart phones, tablet computers, PDAs, digital cameras or notebooks. Besides, with the improvement of microprocessors, portable products are configured with more enhanced functions, but at the same time, the power consumption thereof is also increased a lot.
FIG. 1A is a schematic diagram of two adjacent pixels PA and PB of a conventional LCD apparatus, and FIG. 1B is a schematic diagram of the signals driving the pixels PA and PB in FIG. 1A.
In FIG. 1A, the coupling capacitance CC1 is electrically coupled to the pixel electrode VA and the scan line G2, and the coupling capacitance CC2 is electrically coupled to the pixel electrode VB and the scan line G1. In FIG. 1B, the scan signals (still denoted by G2 and G3) of the scan lines G2 and G3 have two voltage levels, such as 22V of a high voltage level VGH and −7V of a low voltage level VGL. During the period T1, the scan signals G3 and G2 respectively enable (turn on) the switch elements SA and SB, and thus the data signals (voltage level of 0.5V for example) are respectively inputted to the pixel electrodes VA and VB, so that the pixel electrodes VA and VB respectively have voltages of 0.5V. During the period T2, the scan signal G3 disables (turns off) the switch element SA while the scan signal G2 continuously enables the switch element SB, and meanwhile the data signal (voltage signal of 6.5V for example) is inputted to the pixel electrode VB, so that the pixel electrode VB has voltage of 6.5V.
The scan signal G3 down to −7V from 22V at the time t2 will cause a feedthrough effect to the pixel electrode VA, and meanwhile the capacitive coupling effect is caused by the parasitic capacitance between the drain and source of the switch element SA. Therefore, the pixel electrode VA will go down to, for example, −0.5V from 0.5V (i.e. a 1V drop) for the first time. Besides, when the scan signal G2 goes down to −7V from 22V at the time t3, another capacitive coupling effect will be caused to the pixel electrode VA by the coupling capacitance CC1, making the pixel electrode VA go down to, for example, −5.5V from −0.5V (i.e. a 5V drop). In other words, only by applying 0.5V to the data line Data, the pixel electrode VA can achieve −5.5V for the negative polarity operation of the pixel PA. Thereby, compared with the negative polarity operation of the pixel in the conventional art, the data line here has a smaller voltage swing (i.e. smaller difference of the highest and lowest voltage levels) so that the power saving can be achieved.
However, for the pixel PB, because the scan of the scan line G1 electrically coupled to the coupling capacitance CC2 needs to finish before the scan of the scan line G2, the pixel electrode VB that has been charged to 6.5V at the time t3 is just affected by the feedthrough effect induced by the transition from a high voltage level to a low voltage level of the scan line G2, so as to go down to 5.5V (i.e. 1V drop), and meanwhile the pixel PB is on the positive polarity operation.
Therefore, it is an important subject to provide a liquid crystal display apparatus and a driving method thereof wherein the swing of the operating voltages of positive and negative polarities of the data line can be reduced for decreasing the power consumption of the data driving circuit and thus achieving the power saving.